Abstract: Objective To carry anatomical observation and measure on L1 to L5’s length from dural sac’s“axilla”to near-end of ganglion, roughness of nerve root, angle between nerve root axis and midcourt line of dural sac and analyse the clinical signiifcance of nerve roots. Methods In 12 bodies fastened by formalin, we took out vertebral plate in the lumbar vertebra’s superior articular process and inferior articular process with scalpel and lamina impingement rongeur, exposed bilateral dural sac and nerve roots. Isolate nerve roots of L1-5, and conducted elevant observation and measure. Results The nerve root become longer and longer from L1 to L5, L5 was the longest, achieving (12.25±3.66) mm(left), (12.83±2.81) mm(right);roughness become rougher, L5 was the roughest, reaching (3.82±0.88) mm(left), (3.89±0.95) mm(right). The angle of nerve roots became smaller, from (44.33±10.36)°(left), (42.12±10.42)°(right) to (27.33±8.15)°(left), (27.50±8.25)°(right). Conclusion From L1 to L5, the angle between nerve root axis and midcourt line of dural sac become smaller. The length from dural sac’s“axilla”to near-end of ganglion become longer. The roughness of nerve root become rougher. There is no obvious difference between left and right.

Key words: nerve root, dissection, morphology